The ground states of BN molecule under different strong electric fields ranging from -0.06 a.u. to 0.06 a.u. are optimized using density functional method B3LYP at 6-311++g(d.p) level. Optimized parameters, dipole moment, charge distribution. HOMO energy, LUMO energy, energy gaps, infrared spectrum are obtained. The result shows that with the increasing of the external electric field, the correlation between molecular structure parameters and the electric field intensity becomes obvious and presents the asymmetry. In addition, TDDFT method at the same level is used to study the influence of external electric field on BN molecular excitation energy and oscillator strength, and the result shows that the electron transition spectrum is blue-shifted with the increase of the external electric field, but the intensity of the vibrator has a more complicated change, showing that the spectral intensity is affected by the electric field.